Materials Research Science and Engineering Center

2010

The MRSEC Microfluidics Facility

Seth Fraden, Brandeis University, DMR-0820492

Collaborations with Facility Users

• During the academic year, F09 – S10, Dr. Kim, the facility director ,designed, built and tested devices for a number of MRSEC and outside users.
• (a) Microfluidic Device to Study of the Structure of Chromosomes (Dr. Wiggins). This is part of the “confined polymers” thrust. The origin of replication of the E‐coli chromosomes is labeled with a parB‐GFP fluorescent fusion protein to track the locus dynamics in live cells during chromosome replication. The cells are loaded using a permeation pump designed into the microfluidic device which is made from agarose gel so that drugs and growth media can be infused into the cells.
• (b) Top view of a Microfluidic oxygenation device for brain tissue culture (Prof. Lisman) to study neurons. Gas and fluid channels are separated by a thin (5 micron) PDMS membrane.

Outreach

Seth Fraden, Brandeis University, DMR-0820492

The 40th New England Complex Fluids Workshop September 18, 2009, at Brandeis University. The concept of these quarterly workshops is to gather researchers in the field of Soft Matter who work within a two hour drive of Boston in order to promote collaboration and sharing of resources.

The 40th NECFW featured two hours of “soundbites”; five minute summaries of work in progress. It is surprising how much information can be conveyed in such a short time. Equally important was the discussion and networking during breaks and lunch.

2009

Active Emulsion

Irv Epstein, Seth Fraden, Bing Xu, DMR-0820492

Stabilized emulsions containing the oscillating Belousov ‐ Zhabotinsky chemical reaction (BZ) show interesting dynamics. Each drop acts as an independent chemical clock. However, they chemically communicate and exhibit collective behavior. In (a) six BZ drops are contained in a 1D capillary. The white bars are light, which set the oscillators in the reduced state. Drops 1 & 6 are always exposed to light, setting the boundary conditions. Drops 3 & 4 are exposed to light for 0.5 periods. (b) A space‐time plot of the oscillations. White corresponds to the oxidized state; black to reduced. The drops adopt a dynamic oscillatory state predicted by theory. (c,d) Photograph and schematic, respectively, of experimental set‐up. Study of these systems will elucidate a variety of chemically dynamic systems, ranging from neurons to Active Matter –polymeric systems which can convert chemical energy to mechanical motion.

International Collaboration Rwanda

Seth Fraden, Brandeis University, DMR-0820492

Kigali Institute of Science and Technology (KIST). In summer 2009, Prof. Fraden was a visiting lecturer at KIST, teaching an advanced course on laser physics to 37 students shown below. KIST offers two tracks in applied physics; materials and renewable energy. During the visit Prof. Fraden and the chair of physics at KIST, Prof. Onyango, signed a MOU between the Brandeis physics dept. and KIST including enrolling KIST students in PhD programs at Brandeis. Currently there is no post‐graduate training in science in all of Rwanda. An agreement for exchange of faculty between MRSECs and KIST is being formulated.

Polymers Under Constraint

Zvonimir Dogic, Seth Fraden, Michael Hagan, DMR-0820492

fd virus is a polymeric virus 1 μm in length and 10 nm in diameter. We bind fluorescently labeled fd to 1 μm diameter polystyrene spheres creating a charged polymer stabilized colloid (hairy bead) and measure the interparticle potential using a double laser trap. We first measure the interaction energy of (a) bare beads and (b) then the hairy beads, seen here in fluorescence microscopy. (c) Electron micrograph of hairy beads. The repulsive energy of hairy beads is large when the beads are close. (d) We implement a double laser trap and employ an algorithm developed for computer simulations to measure the interaction potential as a function of ionic strength.

2008

MRSEC / SCOPE

Brian Storey Olin; Dongshin Kim, Seth Fraden, Brandeis DMR-0820492

Olin Senior Engineering Project

During the academic year, F08 – S09, Olin undergraduates Sean Calvo, Caitlin Greeley, Stephani Gulbrandsen, and Leif Jentoft designed, built, and tested a flexible automated microscopy platform
capable of imaging an area up to 100mm x 100mm with a resolution of 10 microns at 4.8 second per square mm. It reduces the cost of performing microfluidics research and increases the speed by allowing researchers to easily reconfigure and expand the system to their changing needs.